I haven't booked my assistance because I only need it at the airport, whom should I ask?
Other questions on the same topic
How can I request for a special assistance?
In order to get a service adequate for your needs, as well as a prompt one, the request for the assistance must be forwarded to the Airline already while booking or anyway within 48 hours from the departure time.
It will be the Airline's duty to inform the concerned airport.